One (1) of the major pathologic responses found in human disease is the granuloma-a cluster of cells involved in mounting a hypersensitivity immune response to an antigen or infectious agent. Such granulomatous disorders are histologically classified as caseating granulomas (e.g. tuberculosis and certain other infectious diseases) and noncaseating granulomas (e.g. sarcoidosis). Such diseases are of great public health and scientific importance, in light of how commonly they occur and how often the etiologic agent remains unknown. Sarcoidosis is a systemic form of granulomatous disease that can affect multiple organs. 90% of sarcoidosis patients have pulmonary involvement. Described more than 100 years ago, sarcoidosis remains problematic because of the major remaining gaps in our knowledge about its cause, pathogenesis, host risk factors, prognosis, optimal medical management, and therapy. Approximately 40/100,000 people are affected by sarcoidosis in the United States. Despite significant gaps in our knowledge, notable advances have been made in our understanding of sarcoidosis and, by analogy, other granulomatous disorders as well. Toward the goal of improving our understanding of these disorders, an international, non-profit, medical and scientific professional organization, the World Association for Sarcoidosis and Other Granulomatous Disorders (WASOG), was chartered in 1984 and later founded an international journal Sarcoidosis. Vasculitis and Diffuse Lung Diseases. The WASOG organization is composed of members of the academic medical communities from every continent, with more than 350 members. Every 3 years, WASOG convenes an international conference to examine the latest progress in science and clinical medicine regarding sarcoidosis and related granulomatous disorders and to promote international collaborative research. WASOG 2005 program sessions include: Etiology of Sarcoidosis: a) Genetics and Phenotype; b) Infectious Agents; and c) Environmental Exposures; Immune Mechanisms of Sarcoidosis; Confronting The Complexity of Pathogenesis; Advances in Diagnosis and Management of Sarcoidosis and Other Granulomatous Diseases; and Advances in Treatment of Sarcoidosis and Other Granulomatous Diseases. In addition, 3 separate abstract sessions are planned. We seek support from the NIH for the 8th International WASOG Conference, to be held in Denver, Colorado, June 12-15, 2005. Relevance to the public: Sarcoidosis affects millions of people in the United States. It can be disabling, and can affect many members of a family, yet we do not know its cause, how to cure it, or how to treat it effectively in all patients. The World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) conference is held every 3 years to bring together the leading scientists and researchers, from around the world, studying sarcoidosis. The conference goal is to help current and future sarcoidosis patients by improving our understanding of the cause of sarcoidosis, how the body's immune system acts in sarcoidosis patients, and how to correctly diagnose and treat sarcoidosis.